Published European patent application No. 0 179 185 (corresponding to U.S. patent application Ser. No. 741,247) describes a chair of the afore-mentioned kind. The back rest support of this known chair is designed to be a one-pieced strut and is secured in clamping means provided on the seat, or on the support carrying the latter. After releasing a clamping screw, this back rest support, together with the back rest carried by it, can be shifted vertically and subsequently refastened by manipulating the clamping screw. Such a vertical adjustment of the back rest is complicated. In addition, the structural design does not readily lend itself to being packaged and dispatched because the relatively long back rest support is attached in its entirety to the back rest, this part therefore being very unwieldy.
It is also known to attach the back rest support in one piece to the seat, or the seat support, and to provide a displaceable clamp connection on the back rest itself. In this case, similar difficulties are encountered.